JPS61237564A - Image information reader - Google Patents

Abstract

PURPOSE:To eliminate the disturbance of sub-scanning and to obtain a picture having high quality preventing the deterioration of picture quality during the time when the speed is changed by changing the sub-scanning speed gradually and reducing the load of drive mechanism. CONSTITUTION:When a gate control signal G from a timing generator 17 is H level, a buffer read/write controller 13 writes the data from A/D converter 12 on line buffer 15 which is presently allotted and if the gate control signal G is L level, it does not write. Also the controller 13 notifies the number N of the buffers already written on to the timing generator 17 and the timing generator 17 outputs the variable speed motor drive pulse signal P to a sub-scan drive motor 16 and controls the speed of sub-scanning. Also it generates a gate control signal G and permits the transfer from the A/D converter 12 to the buffer 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an image information reading device suitable as an image data input device for facsimiles, digital copiers, computers, and the like.

[Prior art] In this type of image information reading device, it is necessary to change the sub-scanning speed depending on the next stage of processing such as sending image data to the host or data compression, and to perform the reading scan in accordance with the next stage of processing. There is. For this reason, in the past, the sub-scanning speed was adjusted by repeatedly starting and stopping, but with this method, when a fast scanning speed was required, sudden starting and stopping were repeated, and the drive system As a result, image quality deteriorates due to disturbances in sub-scanning.

Therefore, recently, a system has been developed for high-speed image information reading devices that smoothly varies the sub-scanning depending on the processing speed of the next stage. An example of this is shown in FIG.

In the figure, 1 is a light receiving element such as a CCD, 2 is a variable gain video amplifier, 3 is an interface circuit for a next-stage processing circuit 4, and 4 is a next-stage processing circuit such as a data compression circuit. 5 is a sub-scanning drive motor, and 6 is a timing generator.

Now, when a status signal eusv indicating that processing is currently in progress is applied from the next-stage processing circuit 4 to the interface circuit 3, the interface circuit 3 instructs the timing generator 6 to delay generation of timing. As a result, the sub-scanning drive motor 5 begins to rotate slowly, and the sub-scanning becomes slow. At the same time, the light receiving element 1
The synchronization signal S'/NC for the same time is also delayed. For example, a CCD is used as the light-receiving element 1, but as a result, the exposure time of the CCD becomes longer, and the CCD output increases even if the original density remains the same.

To compensate for this, a gain control signal CC is applied from the timing generator 6 to the variable gain video amplifier 2, so that if the original density is constant, the output of the video amplifier 2 is constant regardless of the sub-scanning speed. There is.

According to this method, the III scan drive motor 5 is driven smoothly without repeatedly starting and stopping abruptly, and therefore image information can be read without disturbance in sub-scanning.

However, in the conventional method described above, the gain of the video amplifier 2 must be accurately controlled according to the sub-scanning speed, making it difficult to maintain accuracy, and since the CCD output varies greatly from line to line, dynamic It had the disadvantage that it was difficult to secure a range and could not obtain high-quality image information.

[Purpose] The present invention reduces the load on the drive mechanism by smoothly varying the sub-scanning speed, thereby eliminating disturbances in the sub-scanning, preventing deterioration of image quality during variable speed, and obtaining high-quality image information. The purpose of the present invention is to provide an image information reading device that allows

[Configuration] In order to achieve this object, the present invention provides a buffer,
While adjusting the sub-scanning speed depending on how much image data has accumulated in the buffer, a synchronization signal is always given to the light receiving element at a constant timing to extract one image data, which is sent to the buffer at a rate according to the sub-scanning speed. It is characterized by being designed to be written.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block configuration diagram of an image information reading device according to an embodiment of the present invention, in which 11 is a light receiving element such as a CCD, 12 is an A/D converter, and 13 is a buffer 7. A write controller 14 is a next-stage processing circuit such as a data compression processing circuit. 15 is a buffer for several lines, 16 is a sub-scanning drive motor, and 17 is a timing generator.

In this embodiment, the buffer 15 is composed of a plurality of line buffers, but it goes without saying that the buffer 15 is not limited to line buffers.

If the gate control signal G from the timing generator 17 is at rHJ level, the buffer 7 read/write controller 13 transfers the A/D converter 1 to the currently allocated line buffer.
Write the data from 2, and the gate control signal G becomes “L”
If it is at the level, do not write.

There is also a request for data from the primary stage processing circuit 14.

Moreover, if there is a line buffer that has already been written at that time, data is sequentially sent to the next stage processing circuit 14 from the oldest line buffer. If there is no line buffer in which data has already been written, data transmission is stopped. In addition, the buffer read/write controller 13
is the number N of buffers that are currently already written (0≦N≦
4) is notified to the timing generator 17.

The timing generator 17 outputs a variable speed motor drive pulse P based on the value of N from the buffer 7 read/write controller 13 to the sub-scanning drive motor 16 to control the speed of sub-scanning. Also, a gate control signal G is generated to
/Permits data transfer from the D converter 12 to the buffer 15. Further, the timing generator 17 always outputs a synchronization signal S of a constant period to the light receiving element 11.

In the above configuration, assuming that the sub-scanning drive motor 16 is a step motor, the speed is changed in units of four steps, and the number of lines of the buffer 15 is four, the reading scan of one image information is performed as follows.

First, the timing generator 17 determines the sub-scanning feed speed F of the sub-scanning drive motor 16 as shown in FIG. 2 in accordance with the number N of lines currently stored in the buffer 15.

That is, at the start of the reading scan, the number of lines already stored in the buffer 15 is N=0, and the sub-scanning feed speed starts from a low speed of F=1. The image data for l lines scanned at the sub-scanning feed rate F=1 is stored in the buffer 15, but if the number of stored lines is N≦2, the sub-scanning feed rate is F=1.
2 medium speed. Even if F=2, if one line of image data is output to the next stage processing circuit 14 and N≦1, then F=3.
The high speed of On the other hand, if N=2 and balanced, F=
Keep 2, but.

As a result of setting F=2, if the number of stored lines increases to N13, the speed is returned to the low speed of F=1. Further, as a result of setting F=2, if N=4, the sub-scanning feed is stopped at F=0.

In this way, the timing generator 17 determines the sub-scanning feed rate F of the sub-scanning drive motor 16 based on the number N of lines stored in the buffer 15 and the previous sub-scanning feed rate F.
When = 1, two motor drive pulses P are applied at a certain period (synchronous signal period), when F = 2, three motor drive pulses P are applied, and when F = 3, four motor drive pulses P are applied. is applied to the sub-scanning drive motor 16.

The sub-scanning drive motor 16 receives one pulse P, 1
Step rotation.

Now, as shown in the time chart of FIG. 3, image information is read and scanned, and the number of lines stored in the buffer 15 is N=2. Assume that the sub-scan feed rate is F=2, and therefore, the reading scan of the 8th line is executed with 3 pulses in the synchronization signal period. At this time.

Since N=2, the timing generator 17 generates the synchronization signal S! The buffer read/write controller 13 is synchronized with the occurrence of the rQJ step of the motor drive pulse P.
The gate control signal G output to the buffer 15 is set to the rlJ level, and writing of image data to the buffer 15 is permitted.

Further, the timing generator 17 determines the value of F in synchronization with the synchronization signal Ss', and determines the number of motor drive pulses P to be output in one signal period.

The buffer read/write controller 13 operates when the gate control signal G is rHJ and the write request signal V is rH.
1 image data A is sent to the A/D converter 12 at the timing of J.
Furthermore, the timing generator 17 once writes to the buffer 15 from the buffer read/write controller 1.
3 starts writing the image data A, and at the same time lowers the write request compensation to the rLJ level.

As a result, while the light-receiving element 11 is reading and scanning the 8th line, the image data of the A-th line read previously is written to the buffer 15.

N is incremented by +1 when writing is completed, and -1 when reading is completed. The value is always incremented by 1 at the time when the synchronizing signal S is generated. However, the time when it is -1 is the next stage processing circuit 1.
It is determined by the processing timing in step 4.

When the reading scan of the B-th line is completed, the image data of the A-th line is stored in the buffer 15, so that N=3 in synchronization with the generation of the next synchronizing signal S2. As a result, F=1, and two pulses P are generated in the synchronization signal period. Further, when the synchronization signal S2 is generated, the write request signal S becomes rlJ due to the generation of the third step of the pulse P, and writing of the B-th line image data to the buffer 15 is started. At the same time as this writing starts, the write request signal V immediately falls to rLJ.

Next, in synchronization with the generation of the synchronization signal S3, the B-th line image data from the previous scan is stored in the buffer 15, and assuming that there is no output to the next-stage processing circuit 14 at this time, N
=4. As a result, F=0, but the synchronization signal 33
At the time of generation, the pulse P is generated at the "1" step, so the pulse P is generated at the same speed as the "2" step and the "3" step. Furthermore, since N=4, the gate control signal G falls to rlJ when the synchronization signal 33 is generated.

The "3" step of the pulse P is generated in synchronization with the generation of the synchronization signal S4. As a result, the write request signal V becomes "old" and since N=4.F=0 at this time, the generation of the pulse P stops, that is, the sub-scanning feed stops.

During this time, it is assumed that the image data in the buffer 15 is read out to the next stage processing circuit 14 and N=3.

In synchronization with the generation of the synchronization signal Ss, the gate control signal G is
Since the write request signal V is rlJ at this time, the C-th line image data read last time is written to the buffer 15, and at the same time, the write request signal V is
Let be rLJ. Also, since N=3 at this time, F=1, and two pulses P are generated in the synchronization signal period.

Hereinafter, in the same way, the timing generator 17 and the buffer 15
The storage state of the image data is monitored and the sub-scanning feed speed is smoothly changed according to the value of N. on the other hand.

The synchronizing signal is generated at a constant period and reading scanning is performed, thereby making it possible to read the image data while keeping the CCI accumulation time constant. The read image data is written to the buffer 15 if N<4, but this writing is also executed according to the sub-scanning feed speed, that is, the pulse P generation rate. This eliminates the need for conventional complicated control such as controlling the gain of the video amplifier according to the sub-scanning feed speed, making it possible to always read and scan image information with a constant CCD storage time. , high quality image data can be obtained. Note that in this embodiment, when the buffer 15 becomes full, the read image data is discarded, but at this time the sub-scanning feed speed also slows down, and the image information that is omitted is only for four steps at most. It has little effect on image quality.

[Effects] As described above, according to the present invention, changes in the sub-scanning feed speed are smoothed, sub-scanning disturbances are eliminated, and the reading scanning time can be kept constant, resulting in high-quality image data. You will be able to do it.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of an image information reading device showing an embodiment of the present invention, FIG. 2 is a state transition diagram of the sub-scanning feed speed in FIG. 1, and FIG. 3 explains the operation in FIG. 1. FIG. 4 is a block diagram of a conventional image information reading device. 11... Light receiving element, 12... A/D converter, 13.
...Buffer read/write controller, 14...
Next-stage processing circuit, 15... Buffer, 16... Sub-scanning drive motor, 17... Timing generator. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] In an image information reading device that performs scanning for reading image information by varying the sub-scanning feed speed depending on the processing status of the next stage, a buffer stores image information to be passed to the next stage, and the image information storage of the buffer is set so that the sub-scanning feed speed is changed. a means for making the reading scan in the main scanning direction variable in accordance with the amount; a means for performing the reading scan in the main scanning direction at a constant cycle; and a means for writing the image information obtained by performing the reading scan at every constant cycle into the buffer according to the sub-scanning feed speed. An image information reading device comprising: means for executing the image information at a certain frequency.